The use of concrete and other cement containing materials in construction has obvious long-standing advantages. However, their appearance, particularly when used to provide inner or outer walls, floorings and other overtly visible portions of buildings or other structures, has for a long time been considered problematic. While it is common that concrete surfaces dominate the aspect of buildings, their appearance is by many considered to be of low aesthetic value, and does not allow for variety or flexibility in the design of surfaces.
Concrete surfaces can be hidden by the use of claddings, floorings, double ceilings, and the like. All these solutions however serve to hide concrete structural portions from direct view, rather than improve the appearance. Furthermore, concrete surfaces generally have a rough and/or irregular surface structure, such that it is difficult or even impossible to provide concrete surfaces with a defined surface structure, such as with specific shapes, colours or gloss, or with surface structures such as decorations, reliefs, roughness, or the like. It is an objective of the present invention to provide methods for providing cement containing materials for use as structural and load-bearing portions in construction, wherein surface properties may be adapted according to requirements, regarding their shape, roughness, colour, appearance, aspect or the like.
The use of geopolymers as structural building units is known to the skilled person. US 2012/0260594 A1 discloses “geopolymeric cements” formed from precursors having a relatively high alumina content for use as structural building units for improvement of thermal performance.
US 2012/0159877 A1 discloses building panels comprising a geopolymer portion, wherein a core includes a first geopolymer concrete, and one or more protective layers including a second geopolymer concrete are located adjacent to the core.
However, geopolymers have a high alkalinity, which limits their use as structural building units, in particular when large amounts are required. The handling of large amounts of alkaline products presents obvious difficulties.